Tires are usually inflated with gas when the vehicle is stopped, by external compressors and pumps nowadays. These inflation methods are time consuming and require periodical checks of pressure, which the users often fail to observe.
These methods moreover do not ensure optimum inflation of a tire in a situation when the current driving manners differ from the manner the tire was originally inflated for. This affects either the tire itself by extensive wear, or safety, as the tire is not always able to perform as it should e.g. as a result of lower pressure to road surface. The economical point of view is also significant. A badly inflated tire has higher rolling resistance, which increases fuel consumption.
Another method of inflating tires is based on inflating during driving by compressors located in the vehicle. This solution is relatively complicated, it requires a compressor in the vehicle, and transfer of compressed air to the rotating wheel is also complicated.
From the American U.S. Pat. No. 4,432,405 we know a device for pumping tires during driving, consisting of a temporarily deformable bellow, or say a cuff attached to a tire from the outside. The bellow is connected with the inside with a hose equipped with a valve and the second valve connects it with outside environment with atmospheric pressure. This device is attached to the tire with a belt, which is not very convenient and may threaten the traffic safety.
The Russian patent 2106978 presents a device for automatic pumping (inflation) of tires. The device working on the principle of peristaltic pump consists of a deformable chamber inside a tire in the casing or next to the inside wall of the tire on the wall of the tire tube. Deformation of the chamber is caused by rolling of the tire on the road surface. One end of the chamber is connected with the outside environment via a pressure regulator-a hose which shrinks and gets closed at particular ambient pressure, and the second end of the chamber is connected to the inside of the tire via a one-way valve. The described pressure regulator works in principle as a double-way valve. If the pressure in the tire the shrinkable hose connecting the deformable chamber with the outside environment goes through is lower than the critical value of the shrinkable hose is, the gas passes freely through the shrinkable hose in both directions. When the pressure inside the tire exceeds the critical value of the shrinkable hose, this deforms and does no longer enable the chamber to suck gas from the outside environment. On the other end of the deformable chamber there is a valve connecting the chamber with the outside environment of the tire and letting the gas flow from the chamber to the tire only, if the pressure inside the chamber exceeds the pressure inside the tire. When the tire is rolling the part of the chamber originally deformed returns to its original position and sucks the air from the outside environment through the shrinkable hose until it is deformed and closed by predefined pressure in the inside space of the tire. No further air is sucked and the device does not pump the tire until the inside pressure drops under predefined value. Manufacturing of the shrinkable hose and adjustment of the moment of its deformation and thus the maximum pressure in the chamber is technologically demanding.
If the pressure in the tire does not reach the value necessary for inflation of the tire until the end of the working cycle and the shrinkable hose connecting the deformable hose with the outside environment is not closed, the whole inside of the deformable hose is connected with the outside atmosphere before the start of a new cycle, so the pressure inside the whole hose drops to the value of atmospheric pressure. The chamber then starts each cycle repeatedly with just the atmospheric pressure of the outside environment.
Another Russian patent application 94031574 A1 describes a hose-shaped elastic chamber located on the inside wall of the wheel rim axially with the wheel outside the tire. A thrust pulley moves along the hose, which gradually presses the air into the inside of the tire via a non-return valve and also to an additional hose-an appendix, similarly to the peristaltic pump. The other end of the hose sucks the air from the outside until the sucking hole gets closed by the expanded appendix.
The device is relatively complicated.
The patents U.S. Pat. Nos. 4,922,984 and 5,052,456 describe devices for inflating and deflating of a rotating tire consisting of a deformable hose attached to the tire, while the hose at least partly copies the tire circumference. The deformable hose is located outside the tire, for example on the wheel rim, or inside the tire on a special holder. In the first instance, a pulley rolls on the deformable hose, in the latter the hose is pressed between the holder and the tire inside wall as a result of movement of the tire on a road. One end of the hose is open to the atmosphere and the other is connected to the inside of the tire through a one-way valve. Deflation of the tire is ensured by a mechanical factor, which when activated opens the above-mentioned one-way valve for the period of each revolution and deflates the tire.
A chamber designed this way, with just one non-return valve, like the patent RU 2106978 does not enable cumulating of gas in the chamber for more cycles.